diff --git a/src/RFID.cpp b/src/RFID.cpp
index 03b40d5..2b15851 100644
--- a/src/RFID.cpp
+++ b/src/RFID.cpp
@@ -100,6 +100,15 @@ bool RFID::programTag(Com::TagInfoRecord *tagToProgram) {
 		Serial.println("Failed to program tag.");
 		return false;
 	}
+
+	// Programming succeeded, update the tracked ID of the tag.
+	for (uidNode* node = activeTags; node; node = node->next) {
+		// The protocol does not support UIDs other than 4 bytes, so assume it
+		// is the case here directly.
+		if ( *(uint32_t*)(node->uid.uidByte) == tagToProgram->uid)
+			node->tag_ID = tagToProgram->figId;
+	}
+
 	return true;
 }
 
@@ -161,7 +170,8 @@ bool RFID::writeBlock(MFRC522Constants::Uid &uidToRead, byte blockAddr, uint8_t
 		return false;
 	}
 
-	byte size = sizeof(comData);
+	// Take into account the two bytes used only for the read commands.
+	byte size = sizeof(comData) - 2;
 	for (byte& bufferByte: comData)
 		bufferByte = 0;